Heat exchanger



Sept. 1, 1936. w, LlNTERN 2,053,037

HEAT EXCHANGER Filed July 24, 1935 INVENTOR. WILLIAM LINTERN- STATES PATEN FFICE 16 Claims.

. internal combustion or other engines which in operation provide a source of heat.

One of the principal objects of this invention is to obtain a more efiicient transfer of heat from the source of heat to air circulated through the exchanger.

A correlative object is to provide an exchanger in which all of the air passed therethrough is passed into more intimate contact with the source of heat and is more uniformly applied thereto.

Specific objects are to provide a heat exchanger in which the air is so introduced and passed therethrough that all of the parts are protected from overheating and the power required for forcing the air through the exchanger is reduced.

Another specific object is to maintain the outer wall surfaces of the exchanger at a lower temperature by retaining an envelope of cooler incoming air between the outer wall of the exchanger and the heated air therein and separated, from the heated air.

Another object is to provide a heat exchanger having a gradually contracted passage communicating with a gradually expanding passage for conducting the air onto and away from the heat source respectively, whereby directional changes in the flow of air and accommodation of expansion thereof are provided without introduction of eddy currents and other currents tending to reduce the flow.

Another object is to provide a device by which media to be heated is continuously introduced to the heating means substantially co-extensive with the heating surface employed, and in which the media thus applied to the heating surface is constrained from mixture with that portion of the media which has not yet been applied to such surface.

through a. heat exchanger embodying the pun-- ciples of the present invention; Figs. 2 and 3 are vertical cross sectional views of the heat exchanger taken on planes indicated by the lines 2-2 and 3-3 of Fig. 1;

ing through the pipe,-both when the heater is Fig. 4 is a perspective view of one of the Venturi elements of the heat exchanger; and

Fig. 5 is a fragmentary left end elevation of the partition wall and support for the Venturi element. 5

For the purposes of illustration, the heat exchanger will be described as a heater for auto mobile passenger coaches in which the exhaust pipe of the engine is employed as the source of heat, its uses in connection with other apparatus being readily apparent therefrom.

Referring to Figs. 1 to 3 inclusive, the heater comprises a hollow body such as an elongated casing l, which is preferably sheet metal and cylindrical in form and, if desired, may be insulated in the customary manner. The casing l is closed at the ends by annular end plates 2 and 3 securely fitted to the casing portion I to prevent leakage 'of air therefrom. Near one end of the casing is a radially extending air inlet duct 4 through'20 which it is connected to a suitable source of air above atmospheric pressure. In the embodiment illustrated, this source of air may be a blower type of fan 5, of the capacity suitable for the particular requirement of the heater. Near the opposite end of the casing is a radially extending air discharge duct 6 for delivering the air to a suitable conduit system or point of application. Heat is supplied to the interior of the casing I through an exhaust pipe 1 which is preferably of cast iron and which may be a continuation of the exhaust pipe of the engine of the automotive vehicle. In the form illustrated, the hot products of combustion from the vehicle engine, or the heating media from the source utilized, are delivered by the pipe I from the end adjacent the inlet 4, as indicated by the arrow.

The pipe 1 preferably extends axially of the casing i and entirely therethrough endwise so that, when used in connection with or as a continuation of the engine exhaust pipe, accumulation of acids and the like, resulting from condensation of the exhaust products, will be prevented, the exhaust products continuously passheated to too intense a degree while other parts admitted for heating be applied to the source of heat or, in this instance, the pipe l, over the entire surface thereof so as to more effectively receive the heat. This air, when heated necessarily will expand, and adequate provision must be made for this purpose. Here it should be noted that in prior heaters of the exhaust gas type, the

general practice has been to admit the air between the casing and the heating source and remove it from the end of the casing opposite to the end at which it was admitted, a large annular passage being provided between the casing and the pipe for this purpose. Thus part of the air came in close contact with the source of heat while another and larger portion did not contact with the source to any appreciable degree but was heated by convection and mixture with the hotter air adjacent the pipe. Usually, also, the air so applied, due to eddy currents and like effects, swirled about the source of heat actually contacting with the source at a few separated zones along its length. This resulted in an increase in the power required for supplying the air, in inefiicient heating of the air, and in the creation of hot and cold spots on the exhaust pipe within the heater. Consequently, not only was the heating efliciency of prior structures low but parts of the exhaust pipes and heaters themselves were remained relatively cool. This unequal heating created twisting, warping and uneven expansion. Other parts of the heaters, and pipes, likewise, were heated to scaling temperature with resultant damage and rapid deterioration.

In order to eliminate these disadvantages, while at the same time obtaining the advantages above recited and decreasing the resistance of flow of air through the heater, Venturi elements Ill are pr0vided.in the present structure. Each element I0 comprises a sheet metal or cast channel of generally U-shaped cross section as illustrated in Fig. 4, having U -arms Illa and a bottom wall Iflb. These elements are assembled within the casing parallel to the pipe I with the free ends of the U-arms IOa disposed adjacent the pipe I, the arms-Illa extending generally radially toward the casing I. The elements are spaced from each other circumferentially of the pipe I and easing I so as to form a plurality of longitudinally extending channel ways, the space II between the adjacent walls I 0a of each pair of adjacent elemerits respectively, being of gradually decreasing cross section from its outer limit toward the pipe I. Near the discharge end of the casing, each of the elements III is disposed with its bottom wall Illb in slightly spaced relation radially to the casing I. The arms Illa are of gradually diminishing radial dimension from the discharge end to their opposite end adjacent the intake 4, between the bottom wall Iflb and easing I, so that the spaces, indicated at I2 in Fig. 1, are of gradually decreasing area from the intake end toward the opposite end of the heater.

Each of the Venturi elements It! is fitted at its smaller end between suitable shoulders I3 formed on the inner wall of end plate 2. At the discharge ends of the elements there is provided an annular partition wall or spider I4 having a plu'- rality of openings I5, eachopening corresponding to one of the elements III. Suitable flange shoulders I 6 are provided on one face of the partition wall I4 which fit about and receive the discharge ends of the elements ID, the engagement between the elements I0 and both the shoulders I3 and I6 being such that leakage is substantially eliminated therearound. The partition It is secured in place for maintaining the elements ill in proper position. The partition wall It entirely seals the inlet portion of the casing I from the outlet portion except for the openings I5.

It should be noted that difficulty is encountered in supporting any such elements intermediate the ends,'as such support would tend to block the flow of air through the heater and cause eddy currents. On'the other hand, the elements must be sumciently strong so that when heated, they will not warp or break, even under the vibrations necessarily imposed in use on a motor vehicle. The U-shaped or channel structure of the elements I0 is such as to render them very strong and rigid so that they may easily be supported only by the ends, as described.

The arms Illa of the elements Ill terminate at their free ends in slightly spaced relation radially from the pipe I, as indicated at I8. 'In the form illustrated, in which the casing I is 20 inches long and 6 inches in diameter and the exhaust pipe 3% inches in diameter and other parts in proportion, the passage I8 may be $4; of an inch in radial dimension. These passages are preferably coextensive longitudinally with the elements Ill, though portions of the free ends of the arms may have means engaging the pipe I to assure accuracy in the width of the passages I8.

In operation air is introduced through the duct d and necessarily fills the casing I. This air then passes from the space I2 into the contracted spaces II between the elements I0 and through the passages I8, whereupon it passes into and along the channel ways provided by the. elements I0, and isthus constrained from mixing with the incoming air. The passage of air through the passages I8 is along the entire length thereof, at all times. Necessarily, therefore, all of the air passes in close intimate contact with the pipe I, as indicated by the arrows 20, so that the entire circumference and length of the pipe is bathed simultaneously by a thin layer of cool, fresh air, uniformly applied. All air passing through the heater must, of necessity, be brought into direct and intimate contact with the pipe I or source of heat. This air, having been heated and having passed into the channel ways provided by the elements I0, is separated from the cooler incomlng air so that a substantially continuous unidirectional flow is obtained. Due to the fact that the spaces II are gradually contracted in the direction of flow of the air, eddy currents and the like are eliminated or greatly reduced.

Since the casing I is substantially unobstructed at the inlet end, adjacent the duct 4, the air may readily-surround all of the elements Ill. Furthermore, since the space between the outer circumferential walls of the elements Ill and the casing is gradually contracted toward the partition wall I4, the distribution of air along the pipe is substantially uniform. At the same time, the layer of air passing'through the space H prevents any appreciable loss of heat from or heat transfer to the casing I. As the air within the elements I0 is heated to a high degree and the elements themselves become heated accordingly, any heat the amount being additive from the inlet end to the discharge end. The opposite is true in regard to the passage or space H. By forming the elements ID with a gradually increasing cross sectional area or radial dimension in the direction of flow, both this expansion and the added quantities of air may be readily accommodated.

As the air leaves the openings l5, it is already comparatively uniformly distributed around the circumference of the pipe 1 so that the short intervening section of pipe, between the wall It and the end plate 3, is likewise bathed with air entirely around its circumference.

Thus, by this arrangement, a Venturi effect is provided in that the contracting spaces i l form the inlet of the venturi in which the air may be gradually contracted and from which it is immediately discharged through the passages l8,

which correspond to the Venturi throats, into present.

While I have described the above invention particularly in connection with exhaust heaters for automobile vehicles, it is apparent that advantageous results efiected may be readily embodied in structures utilizing other sources of heat, the heating media being supplied in the pipe I. It should be noted, however, that the proportions of the structure may be changed. In automotive use the exhaust heat is usually wasted, consequently any use thereof is a direct gain. Merely for obtaining all the heat in the pipe I, it is usually sufiicient to lengthen the heater, a limitation, however, being present in that undue increase in length of the heater may result in buckling of the elements l when heated. To increase the quantity of air required, it is more desirable to increase the diameter of the casing, the elements I0 and the passages above described being correspondingly increased. In such instance, however, are must be taken that the passages ii! are not too greatly increased because, if they are increased unduly, the very purpose sought to be eifected will be defeated, namely; the application of all of the air as a thin layer uniformly distributed in sufficiently close proximity to the pipes I;

Having thus described my invention. I claim:

1. A heat exchanger comprising a hollow body having an inlet for media to be heated and an outlet spaced from'the inlet, a heating element extending within the body in spaced relation to the wall thereof, a plurality of Venturi elements interposed between the body and the heating element and interposed between the said inlet and outlet for receiving said media admitted by the inlet and directing said media into intimate contact with the heating element, said elements pro viding passages for reception of the said media after passage of said media into contact with the heating element and for conducting the separated media to the outlet.

2. A heat exchanger comprising an elongated heating element, means surrounding said element and defining an inlet passage to the heating element for media to be heated, means for supplying said media through said inlet passage, said inlet passage being of gradually decreasing cross section in the direction of flow of said media and discharging onto said heating element, and a discharge passage for said media communicating at its inlet with the outlet of the inlet passage for conducting said media along said heating element, said discharge passage being of gradually increasing area in the direction of flow of said media.

3. In aheat exchanger of the character described, a heating element, means surrounding the element and providing an inlet passage for media to be heated, said passage being gradually contracted in the direction of flow of said media therethrough and discharging onto the element, and a discharge passage for said media gradually expanding in the direction of flow of said media therethrough and leading from the discharge of the inlet passage and along said element.

4. In a heat exchanger of the character described, an elongated casing having an inlet for media to be heated at one end and an outlet at the other end, a heating element extending longitudinally of the casing in spaced relation to the side walls thereof and entirely therethrough for supplying heat within the casing, a plurality of Venturi elements comprising a series of circumferentially spaced radially extending channels mounted within the casing in spaced relation to the side walls thereof and being open toward the heating element, the free ends of the channel side walls terminating in slightly spaced relation to the heating element, said Venturi elements being of substantially uniform width and being spaced apart around the axis of the heating element between their outer and inner radial limits, whereby spaces gradually contracted toward the heating element are provided between adjacent Venturi elements, which spaces communicate with the interior channel ways of said Venturi elements around the free ends of the side walls thereof,

said Venturi elements extending longitudinally of said heating element from adjacent the said inlet to adjacent the said outlet, and the channel ways of said Venturi elements discharging into the outlet.

5. A heat exchanger comprising a hollow body having an inlet and an outlet spaced apart from each other, means to supply a current of media to be heated through the body from the inlet to the outlet, a heating element extending within the body in spaced relation to the walls thereof, means interposed between the body and the heating element for directing said media from the inlet and constraining the media to flow in .a thin sheet in surrounding and intimate contact with the heating element; and providing a passage for reception of the media after passage thereof into said contact with the heating element and for conducting the heated media to the outlet.

6. A heat exchanger comprising a hollow body having an inlet and an outlet spaced apart from each other, means to supply a current of media to. be heated through the body from the inlet to the outlet, a heating element extending within the body in spaced relation to the walls thereof, means interposed between the body side wall and the heating element in spaced relation to both for directing media from the inlet passage onto the,

media out of contact with the cooler incoming media.

7. A heat exchanger comprising a body having an inlet and an outlet, means to supply a current of media to be heated into the body through said inlet, heating means in the body extending lengthwise between the inlet and outlet thereof and spaced from the side wall of the body, means within the body extending along the heating means in spaced relation thereto and to the surrounding body wall and forming a passage for conducting the media along the heating means to the outlet.

8. In a heat exchanger of the character described, an elongated casing having an inlet for media to be heated at one end and an outlet 'therefor at the other end, a heating element extending longitudinally of the casing for supplying heat within the casing, means within the easing dividing the incoming media into a series of elongated thin sheets extending lengthwise of the heating element and directing the sheets edgewise generally radially onto the heating element and providing channel ways extending lengthwise of the heating element between the sheets of said media and opening toward the heating element for receiving the said media discharged onto the heating element and for conducting the said media to the outlet. 7 9. A heat exchanger comprising a casing having an inlet for media to be treated and an outlet, means to supply said media into the casing through said inlet, a heating element in the casing, means within the casing for directing the said media onto the heating element into intimate contact therewith, for receiving the said media after its passage into contact with the heating element, and for maintaining the said media being introduced into the casing in surrounding relation to and separated from the said media which has been heated by contact with the I heating element.

10. In a heat exchanger of the character described, an elongated casing having an inlet at one end for receiving a current of media to be' heated, and an outlet at the other end, a heating element extending longitudinally of the casing entirely therethrough for supplying heat within the casing, a plurality of circumferentially spaced radially extending channels mounted within the casing and spaced from the wall thereof and opening toward the heating element, the channel side walls having portions terminating in spaced farther from the casing near the heater inletend and gradually receding from the element toward the heater outlet, whereby more uniform distribution of the incoming media along the element is eflected, all media being passed into intimate contact with the element, and the incoming media being maintained separated from the heated media thereby reducing heat losses from the casing.

11. A heat exchanger comprising a heating element, means surrounding the element and deacoaoar a an inlet passage to the heating element for media to be heated, means for supplying said media through the inlet passage, said inlet passage dischag onto the heating element, and

a discharge passage for said media communicating at its inlet end with the outlet of the inlet passage for conducting said media along said heating element, said discharge passage being of gradually increasing cross sectional area in the direction of flow of said media.

12. In a heat exchanger, a casing, a heating element within the casing, means for circulating media to be heated into, through, and out from the casing, means within the casing and spaced from the heating element and easing side wall and providing a passage for directing the media to be heated along the heating element and providing a passage for conducting unheated incoming media between said last mentioned means and easing wall in enveloping relation to the heated media, whereby transfer of heat to said wall Irom the element and heat radiationlosses from the casing are reduced.

l3.- A heat exchanger comprising a hollow body having an inlet and an outlet for media to be heated, a heating element in the body, means for supplying media to be heated through the inlet, means within the body for subdividing the media intoa plurality of thin sheets extending along the heating element and for directing the sheets into edgewise initial contact with the element simultaneously at diiferent portions of the element and for receiving that portion of the media which has contacted with the element and conducting said portion therealong to the outlet while constraining said heated portion from mixing with the unheated portion of the media.

14. A heat exchanger comprising a hollow body having an inlet and an outlet, a heating element therein, means to supply media to be heated into the body, means within the body for directing the media into initial contact with the heating element simultaneously over the heating surface of the heating element while constraining the unheated portion of the media to enveloping relation with the portion of the media being directed onto and heated by the element and for constraining the enveloping portion of the media from mixture with the heated portion thereof while conducting the heated portion of the media to the outlet.

15. A heat exchanger comprising a body having an inlet opening and an outlet opening, a temperature affecting means in the body between the inlet and outlet openings, a plurality of elements arranged side by side and extending along the said means in spaced relation therefrom and providing channels open toward said means, said elements being spaced apart from each other laterally and providing passages therebetween, said passages being in communication with the channels through the space between the elements and the temperature afiecting means, means connecting the channels with one of said body openings, and said passages between the elements being connected with the other of said body openings.

16. A heat exchanger comprising a body having an inlet opening-and an outlet opening, a conduit extending into the body and uncommunicated with the interior thereof and having an inlet and an outlet arranged exteriorly of the body, a plurality of elements arranged side by side within the body and extending'along the conduit in spaced relation therefrom and protween the elements being connected with the other one of said body openings, whereby media may be supplied through the conduit and other media may be supplied through the passages and channels for affecting heat exchange between the 5 supplied media.

WILLIAM LIN'I'ERN. 

